Receiver



pins 3 project iromthe Patented Jan. 24, 1928.

UNITED STA TES- ERNEST A. BOHLMAN, OF CHICAGO, ILLINOIS, ASSIG-NOB CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

AND SUPPLY COMPANY, OF

To KELLoeG swrronnoaan R CEI ER.

Application filed April 18, 1925. Serial No. 24,022.

My invention relates to receivers and has to do particularly with loud speaker unlts as they are commonly known in the radio art. An object of my invention is the provision of a receiver of this type that is provided. with novel features of construction and assembly that can be constructed readily, that is simple, and most eiiiclent in its operation. 1 p n A feature of my invention is the provision of supporting means for the pole pieces, and associated apparatus, which are supported, as a whole, on springs. I provide adjustable means, associated with the supporting means for moving the supporting means as a whole up or down, in an enclosing cup, to vary the air gap between the pole pieces and the chaphragm to obtain the maximum efficiency for clear and perfect reproduction of sound.

A further feature of my invention is the provision of new and'novel means for trictionally maintaining the pole pleces and their supporting member in any of their adjusted positions, in relation to the chaphragm.

The above features, as Well as others not specifically pointed out, will be more fully described in the following specification and the appended claims. I

For a more complete understanding of my invention reference may be had to the accompanying drawing in which like reference characters in the diiierent views denote like parts and in which;

Fig. 1 is a bottom View of the receiver of my invention;

Fi 2 is a right side View of Fig. 1; Fig. 3 is a sectional view of Fig. 2; and Fig. 4c is a side view of my device with part of the casing cut away and with some of the parts removed to facilitate explanation. 7

Referring to the receiver oii my invention it comprises a. cup-shaped member 2, formed. of any suitable material such as brass, in which is adjustably secured the mechanism oi the receiver. Three pins Bare inserted into suitable orifices provided in the bottom of cup member 2 and their ends are then swaged over to hold them in place. The face 4 of thebase l of the cup member 2 into the interior of the member 2. A disk 5, formed of any suitable material such as brass and of a diameter slightly smaller than that of the cup secured to the cup member 2, is provided with three orifices which are in alignment with the three pins which extend into these orifices when the disk is positioned in the cup 2. Ahelical spring (not shown) is placed around each pin 3 and rests between the face l of the base 4: of the member 2 and the 'f-ace9 oi the disk 5 for purposes as will be described presently. The base A of the cup member 2 and the disk 5 are provided with central orifices 10 and 11 which are in alignment with each other. A threaded stud 12, provided with a slot 13 in its head, passes through the orifice 10 in the base 4; and has screw threaded engagementwith the threadcd orifice 11 in the disk 5. i

A horseshoe shaped permanent magnet 23 constructed of steel and permanently magnetized is placed in the cup member 2. Its

ends are located over the portions 14 and i 15 of the angularly shaped pole pieces 1st and 15 and these portions 14: and '15 rest between the face 7 of the disk 5 and the permanent magnet 23. The angnlarly shaped pole pieces 14: and l5extendupward in proximity to a diaphragm and carry the magnet coils or spools 21 and 22.

The pole pieces 14c and 15 and the permanent magnet 23 are secured to the disk 5 by means of aclamping member 8 .whichlits over the permanent magnet 28 and is provided with tapped orifices which have screw threaded engagement with screws24 which extend through orifices in the disk 5, pole pieces 14 and 15 and into the orifices inthe member 8.. When the screws are tightened their heads rest 1n countersunk portions in the disk 5 and the pole pieces, and magnets are secured in their proper positions. As my invention has more to do with the adjustmg mechanism of the device, it is not i thought necessary to give a further description of the construction and. arrangement of the electromagnetic parts of the same.

Thecup member 2 is provided with exter nal threads 25 at its forward end upon which is secured a cap 26 which is made oi" suit able material such as hard rubber or bakelite. The cap 26 is provided with a protruding portion 27 which has internal threads 28 adapted to receive asuitable sleeve member for connecting it, as a unit,to a projector orhorn. I

A pair of terminals 29 and 30 are suitably member '2 for securing a pair of external] conductors thereto.- A spider 31 which has a central orifice of a size to permit the insertion of the body portion of the threadedscrew 12' is placed in positioneiid is held in fixed relation to the screw 12 by means of a swaging oper ation. The spider has four legs 31. wh'idlt are slightly bent so that they are under tension when the central portion is held against the face 320i the based of the cup member 2. -A plurality of small ridges 33 are stamped into the am 32 of the base t in the form ot-acircle as illustrated in Fig. 1 of theaceoinpan ying drawing. The arms 31 of the spider 31 are provided with slight protnberances upon the bottom side thereof. These protuherancesare stamped so as to he in a longitudinal direction in relation to thearmnsBlqand are adapted to :[it between the ridges33 stamped in the face 32 of the base 4 of the cup member 2. i

The disk 5 andits supported apparatus may be adjusted as a Whole up or down in the eupmember 2 to vary the air gap between the pole pieces 14" and and the diaphragm When the stud 12 is turned in a clock-Wise direction, through the agency of asuitable tool placed in the slot 13 of the stud 12; the disk 5 and its associated parts are drawn farther into the cup-memher 2 against the tension of the -lielical springs ai'oundthepinsES, this movement enlarges the airgap betweenthe pole pieces 14 and 15 and" the diaphragm ,Wnee the stud12 is turned in a counte clockwise directionthe springs around the pins 3 "force the disk 5 and its associated parts upward to lessen the air gap between the diaphragm 20 andthe pole pieces l-land 15. p Thedisk 5 is guided in its different-movements by the pins 3 which extend upward into tliefaligned orifices in the disk These addition to serving as guide inea us for the disk 5,: prevent the disk 5 from tilt mgfin its m vement and from rotating" n hen the stud 12 is turned The spider 31 being rigidly 'fafsteiied to the stud 12 turnswhen the said-stud 12 isturned and the arms 31 eachotwhieh has a slight protuberance on its iiniiler side are caused to travel over the sniall, ridges33iorn1ed on the bottom of the cup member-2. Asbeli'ore explained the arnis 31 have a spring tension and, when the rotation ot'the stud 12 is finished,the-pro tube 'ance's on the under side of arms 31. rest i r 1-4 M ,0 between adpicent ridges; The :tour. arn is all,

Each h'eingiihdersimilar conditions hold the spider 31 and thepstud 121, tohwhieh it is rigidly tastened, in any adjusted position dueto the trictionbetween the armsISLand. the ridges. 3 and prevents. the vibrations ofthe device from changing its adj istn ient. The stud 12 thus being prevented from root ingi the disk: 5 audits associated parts" are also prevented from movement and" conseclaim as new and desire to secure by lihiited State Letters Patenhiis:

1. Aderiee lot the character (lCSCflliiJUil in cludingaeup nienihei", a disk, adiapl ragnn a pair of pole pieces, a magnet; said-pole pieces and said magnet supported on said dislg said diskandi its supported part; being. in adjustable relationship to said dia- V phnagm, and means including a spider ihem- ]ier adapted to engage a ph'n'ality oiridges on said cap member for yieldingly holding said disk and its associated parts in adjusted position in relation to the said diaphragm.

2. Adevice of the cliaractcii described; in: eluding a cupiiieniber, a disk, :1 di'aphru'gnn a pair of pole to said diaphaigm, a stud foradjustingsaid pole pieces in relation to said diaphragm, a d means rigidly secured to saidstud including a spidernieniber adapted to engra e 'a plurality of ridgeson said cup inemi for preventing movement of said pole piecesiiel ative to saiddiaphragm.

A- device of the class described including a cap member, a disksupported in said cap member, a a diaphragm, a pair of pole pieces supported on said disk infadjustahie relationship to said diaphragm, a stud for changing said {r'elationship and means i uclu'ding'a spider I'igidly afiiiiedto said stud for yieldingly holding said pole pie; justed position relative to said diaq ihr 41A device the elassdeseril d iixelhkt ing a cup inenibe al [Humility oi if'idin the bottom tlieretii; a di' ahragm, a i pair oipole pieces supporting menu;mil all supported on said disk ill "I stable relationship to said dia hragm, a stud For changing said relationship; and a spider rieflidl i secured to said studand eue'agziiur said plurality of ridges to hold the pole pieces iuany adjusted position in relation to said diaphragm.

5. A device ofthecharacter described ineludingt a cup-member, a plurality of. ridges on the liottoni thereof, a rotatable stud, a

spideihrigidly aiiii'ed to said stud, a" pluill] pieces in adjustaliile relation ill? 6. A device of the character described ineluding a cup member, a plurality of ridges in circular form on the base of said cup member, an adjustable stud, a spider having a plurality of arms rigidly affixed to said stud and adapted to engage said plurality of ridges, and a protuberance on each arm adapted to engage the adjacent sides of two successive ridges, said arm and said pr0- tuberances adapted to frictionally maintain said stud in adjusted position.

7. A. device of the character described ineluding a diaphragm, an electromagnetmounted below said diaphragm, means for adjusting the position of said electromagnet relative to said diaphragm, and means including a spider member adapted to engage casing and beneath said a plurality of ridges on said cup member for yieldingly holding said adjusting means in an adjusted position.

8. A device of the character described in cluding a casing, a diaphragm for said casing, an electromagnetic coil included in said diaphragm, adj usting means for regulating the position of said coil relative to said diaphragm, and means including a spider member adapted to engage a plurality of ridges on said cup member for maintaining said adjusting means in an adjusted position.

Signed by me at Chicago, in the county of Cook and State of Illinois, this 16th day of April, 1925.

ERNEST A. BOHLMAN. 

